In older system usually there was setting of runlevel called "initd" ,which is currently replaced by "systemd".

Both this system used for initialization of system during boot process . also used for starting & stopping services usually refered as daemon.

The key file in this regard was "/etc/inittab" ,which need to be edited suitablly.

For logging into terminal initdefault need to set as 3

id:3:initdefault:

For logging into graphical mode initdefault need to set as 5

id:5:initdefault:

Initd Equivalent for "systemctl get-default" command is

cat /etc/inittab | grep initdefault

Relating Systemd & Initd

Init RunLevel Systemd Target Run Level Description

0 poweroff.target The halt runlevel - this is the runlevel at which the system shuts down. For obvious reasons it is
unlikely you would want this as your default runlevel.

1 rescue.target Single runlevel. This causes the system to start up in a single user mode under which only the root user can log in. In this
mode the system does not start any networking or X windowing, X or multi-user services. This run level is ideal for system
administrators to perform system maintenance or repair activities.

2 multi-user.target Boots the system into a multi-user mode with text based console login capability. This runlevel does not, however, start the
network.

3 multi-user.target Similar to runlevel 2 except that networking services are started. This is the most common runlevel for server based systems
that do not require any kind of graphical desktop environment.

4 multi-user.target Undefined runlevel. This runlevel can be configured to provide a custom boot state.

5 graphical.target Boots the system into a networked, multi-user state with X Window System capability. By default the graphical desktop
environment will start at the end of the boot process. This is the most common run level for desktop or workstation use.

6 reboot.target Reboots the system. Another runlevel that you are unlikely to want as your default.

Please refer http://www.linuxtopia.org/HowToGuides/runlevel.html for more information on initd